After a fairly standard application I had a video interview, this was a bit awkward as it consisted of pre recorded questions which you recorded your answers to. It felt a bit unnatural but ultimately went fine.
I was then asked along to one of their assessment centres (I attended in London). Started with an introductory talk followed by a quick tour. There were three short assessments on maths, 'IT' and ven diagrams and set notation. The maths test is very basic and they give you a booklet about the ven diagrams but if its not something you've seen before they provide you with revision links that are quite good. The IT test was a bit odd, seemed like a general knowledge quiz come professional aptitude test. Questions ranged from what does HTML stand for to what would you do if one of your colleagues smelled really bad...
After these I had three short (very short, maybe 5 mins) one-to-one interviews.
I was offered the role but rejected it due to the lack of pay for at least 4 but up to 7 months!